Winding mechanism for magnetic recorders



March 9, 1954 F, DE CLERCK WINDING MECHANISM FOR MAGNETIC RECORDERS Filed Oct. 13, 1952 9 J M 5 n v Q o .l M. J 0 T 4 4 L a r .m .9 m MW m m V ma/ar I40 (z (5 t4 [1 t2 Fig.2

I l/Mao; De, o/ere,

19% n a s,

Patented Mar. 9,

WINDING MECHANISM FOR MAGNETIC RECORDERS Fernand de Clerck, Marcinelle, Belgium, assignor to Ateliers de Constructions Electriques dc Charleroi, Brussels, Belgium, a Belgian firm Application October 13, 1952, Serial No. 314,501

Claims priority, application France October 26, 1951 3 Claims. (Cl. 242-75) vention has especial relation to the winding unit of such mechanism.

Copending application, Ser. No. 215,215, filed March 13, 1951, now abandoned, describes a mechanism of this character, the purpose of which is to assure correct operation and perfect magnetic reproduction at any point whatsoever of the tape. More particularly, the mechanism of the said copending application is designed toward the achievement of correct winding of the magnetizable tape onto a winding cylinder or drumsuch winding involving a translational movement of the tape along a path fixed in space-without transverse sliding movement toward either 'of'its edges, and also toward the achievement of a uniform winding without abnormal increase due to enlargement of the diameter of th assembly formed by the winding cylinder and the part of the magnetizable tape already wound thereon.

In the arrangement according to the said copending applicationwhich arrangement, reduced to lowest terms, comprises an unwinding cylinder for the tape, an exploring table over which the tape coming from the unwinding cylinder passes, magnetic heads which explor the tape as it passes over said table, a feed roller device which actuate-s the tape, i. e. imparts translational movement thereto, and a winding cylinder or drum on which the explored tape is wound-the lateral guiding of the tape is assured by the following means:

(a) The speed of advance of the magnetizable tap is solely conditioned by the rotation of, a driving roller;

(1)) The mechanical tension of the magnetizable tape is equalized by springs cooperating with levers which support control rollers, the rotation of the winding and unwinding cylinders being controlled intermittently so as to maintain (a) The winding drum is equipped with a yieldable pressure heel in such manner as to press the successive wound layers of magnetizable tape against one another;

(b) A sheet of metal or of metallized material is interposed between the last two layers of magnetizable tape and slides between them and such sheet, being retained by spring means.

While the construction according to the said application is well suited for its intended purpose, the regulation of the limits between which the mechanicaltension-of the magnetizable tape varies, in the aforedescribed prior mechanism, is quite delicate, so that an accidental slight maladjustment or poorly determined limits can occasion a lateral sliding. The metallized sheet designed to prevent buckling is also sensitive and may on occasion constitute a source of difficulty in the proper operation of the mechanism.

A primary object of the present invention is th embodiment of improved winding mechanism, designed primarily for use in winding and unwinding mechanism of the type of the said copending application, and which is free of the aforesaid inconveniences.

Briefly stated, the new winding mechanismthe unwinding and feeding mechanisms for the magnetizable tape advantageously remaining the same as in the copending applicationhas the following characteristicsi 1. The winding mechanism is constituted by a winding drum or cylinder provided with an individual driving motor, and by auxiliary means designed to impart intermittent rotary movement to said cylinder, the starting of the said driving motor being effected progressively;

-2. The winding cylinder is actuated by an intermittent rotary movement, the angular velocity of which increases gradually from the stat of rest, the said velocity reaching a value such that the linear winding velocity of the magnetizable tape on the said cylinder is greater than the rate of travel of the said tape;

3. The auxiliary device comprises a resistance with a negative temperature coefficient, inserted in series in the feed circuit of the driving motor of the winding cylinder, so that the angular velocity of the said driving motor increases progressively starting from the state of rest;

4. The auxiliary device comprises a switch inserted in series in the feed circuit of the driving motor of the winding cylinder, the said switch being kept closed by a spring, a feeler system in contact with the magnetizable tape also acting on the switch, in such manner that the latter is kept open by the -action of the feeler system when the mechanical tension of the said magnetizable tap exceeds a certain maximum value;

5. The feeler system is made in such a waythat contact with the magnetizable tape takes place only in the median portion of the said magnetizable tape, relatively to its width.

A presently-preferred relationship of j parts'according to the invention is shown diagrammatically and by way of example only, on the accompanying sheet of drawings, wherein;

Fig. 1 is a diagrammatic showing or the rela tionship of parts of the present invention at one stage in the winding operation;

Fig. 2 is a similar showing at a different stage in the winding operation; and

Fig. 3 is a graphic representation of the variation in rotational speed of the motor drivingthe winding drum or cylinder, as a function of the time- Y The magnetizable tape I, -after being .delivered from the unwinding cylinder (notshownl-and after being passed over the exploring tabled, where it is exploredby the magneticheads 4, and between the feed rollersr8tand. 9, is directly wound on the winding drum 5.

According to the characteristics-of" the invention, as hereinbefore defined, the winding mech- .anism has the following particularities:

The winding :drum .5 is fixedly mounted on shaft '50 driven by a'driving motor-I40 (by conventional means, notshown, e. g. a driving-belt .of the like), in.such a way that the maximum .linear windingvelocity of the magnetizable tape Iron the drum .5 is higher thanthe-speed of travel of the-said tape, this'travel- (oradvance move- -:ment) being eilected. by the roller 8 keyed onto shaft 80' driven; by a driving motor (notshown), with the aid' of superposed rollerv 9.

The driving motor I40is, fed from a suitable and conventional source-of current I4I. In series ,in thesupplycircuit, there. are vintercalated 1. resistance I42, with negative temperature coefficient, and a switch-l43. The switch-I43 is .kept .normally closed by .a pull spring I44 in- .tegrally connected with theframeworkof the apparatus, and is controlled by a feelersystem, .showndiagrammatically at I45,.in contact with the magnetizable tape I.

The feeler system itself may be of :any suitable and per se conventionalconstruction. For .ex-

ample, it-may be-a slidably supported rod having ,a loop atone end through whichthe-tape passes, thus assuring contact between the tapeandthe feeler end ofthe rod. The latter is of a length slightly greater than the distance between switch I43-and the tape, when the tape is in --taut.state -(Fig. 2).

The operation of the winding mechanism. is as .follows:

The magnetizable tape I being in thevposition shown in Fig. 1; that is to say in the slack" state, the-feeler device I 45. does not act on-theewitch l-43-and permits-the closing-of this "latter .by the actionof thespring I44, .At-thismomentthe supply circuit ofthedriving motor I40 is closed.

The resistance I42, with negative temperature coeflicient, is: conditioned so that, cold,--its value is-sufiiciently high. and so that, as a consequence ..of the difference of potential at its terminals the voltage-at the terminals of the =motor-l4l$s .in- -suflicient to start-the said motor; the-W- :able band I* therefore continues to-becomem.

4,42 .iprogreesively. diminishes its that the driving motor I40, after having started under a low voltage, is subjected to a gradual, but continuous, increase infeed voltage. The ma netizabletape I is thus wound onto the windin drum 5, keyed onto the shaft 50 driven by the motor I40, and the linear winding velocity of the magnetizable tape I reaches and exceeds the linear rate of travel (advance) imposed by the .drum 8, driven by the shaft 00.

When the mechanical tension of the magnet izable tape I exceeds a maximum admissible value, the action of the feeler device I45 on the switch I43 overbalances that of the spring I44,

. and: the switch- I43 .opens, thus interrupting the feeding of .the driving motor I40. The state shown in'Fig.2 of the drawings is then reached.

Another operating cycle begins when the magnetizable. tape I no longer has sufficient mechanical tension to balance the action of the spring I44.

The graph shownin Fig.3 shows .the. course of the variation of therateof rotation of thedriving motor I40 in time. It can be.seen-.on..this graph that, although the switch I43 .is closedat time tI the .driving motor I 40 I starts only .at. time t2, because of the retarding -.-action.of.the.resistance I42. Between the times t2- andt3 the. rate of'rotation graduallyincreases, and attime t3 the mechanical tension of the magnetizable tape .I is sufiicient for the feelerdevice I45 toopenthe switch I43. The driving motor .isthen .stoppedat time t4.

After a certain time of stoppage a new operating cycle is repeated in t. I ..t4.

It canreadily be appreciated that bythe temporizing effect of the negative resistance I42.inserted inthe supply circuit of the .motor.I40. a

great fiexibilityand smoothness of operationare obtained.

Having thus disclosed the invention, .Whfltll claimed-is:

1. A winding mechanism for winding a magnetic recorder tape or the like onto an intermittently rotatable windingcylinder, comprising means for feeding the tape along :a pathto said winding cylinder, :and .means for v.impartingdntermittent rotation to said winding .cylin'der, said I .last-namedmeans comprising a driving motor for said cylinder and. means foroontrolling-the angular velocity of said motor. wherebysuch velocity and the velocityof the drivenwindins cylinder progressively increasetotheir maximum, starting from .the state of rest, the .meansffor controlling the saidangular velocity comprising .a resistance with a negative .temperatutecoefficient. inserted in. series, in the feed. circuit. of said motor whereby, initially,lthe resistancehas a maximum value and,- as-.the resistance'heats .up, the resistance graduallyand progressively .de-

creases.

2.. A winding mechanism for windinga ma .netic recorder tape or the like .onto an intermittently rotatable .winding. cylinder, comprising .means for continuously feeding-the .tape along a path to said winding cylinder whereby, when said winding cylinder .is not rotating, ,tape..-in

slack state accumulates inthe path between said .cylinder and feeding .means, andmeans for ,pe-.

riodically tensioning said tape in ite-travel from said feeding meansito said-winding cylinder. said tensioning means comprising i an intermittently operated driving motor for :said cylinder,..,the

..maximum ,angular speed of rotation of-which .exceeds the linear speedof, travel of said tape Theheatingby Joules'efiectrof the nlong'saidljpath, anormally closed switch inw gflij mea in series in the feed. circuit of said feeler means in contact with said tape at a point in its travel from said feeding means to said winding cylinder, said feeler means opening said switch when said tape has been tensioned by said tensioning means, and means for controlling the angular speed of rotation of said motor whereby said speed progressively increases to its maximum, starting from the state of rest, the means I for controlling the said angular velocity comprising a resistance with a negative temperature coefiicient inserted in series in the feed circuit of said motor whereby, initially, the resistance has a maximum value and, as the resistance heats up, the resistance gradually and progressively decreases.

3. A winding mechanism for winding a magnetic recorder tape or the like onto an intermittently rotatable winding cylinder, comprising means for continuously feeding the tape along a path to said winding cylinder whereby, when said winding cylinder is not rotating, tape in slack state accumulates in the path between said cylinder and feeding means, and means for periodically tensioning said tape in its travel from said feeding means to said winding cylinder, said tensioning means comprising an intermittently operated driving motor for said cylinder, the maximum angular speed of rotation of which exceeds the linear speed of travel of said tape along said path, a normally closed switch inserted in series in the feed circuit of said motor, feeler means in contact with said tape at a point in its travel from said feeding means to said winding cylinder, said feeler means opening said switch when said tape has been tensioned by said tensioning means, whereby rotation of said motor and winding cylinder stops and said slack again accumulates, means for returning said switch to closed position when said slack has accumulated and means for controlling the angular speed of rotation of said motor whereby said speed progressively increases to its maximum, starting from the state of rest, the means for controlling the said angular velocity comprising a resistance with a negative temperature coetficient inserted in series in the feed circuit of said motor whereby, initially, the resistance has a maximum value and, as the resistance heats up, the resistance gradually and progressively decreases.

FERNAND m: CLERCK.

Number Name Date Spencer et al. Jan. 21, 1941 

